Electrochemical Method to Measure the Defect-Free Zone in Silicon Wafers
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
There is a real need in the semiconductor industry to investigate defects that may create leakage currents in the proximity of the active surface of the wafers (0 to .7 mm depth). Existing solutions such as beveling or MOS retention time techniques are complicated because they necessitate special preparation of the wafers, and are expensive. The present electrochemical method, based on a dissolution step with an efficient etching solution, allows one to reach the surface where defects can exist. The electrical activity of those defects can be evaluated immediately by the measurement of leakage current (cathodic current). The proposed method is basically comprised of two steps: 1) dissolution of silicon, and 2) measurement of the electrolytic reverse current.